The present invention relates to compounds in which a transition metal is complexed with two ligand systems and the two systems are reversibly bonded together by at least one bridge containing a donor and an acceptor, at least one substituent on the acceptor group being a fluorinated aryl radical, to the use of these compounds as catalysts and to a process for the polymerization of olefins.
The coordinate bond existing between the donor atom and the acceptor atom produces a (partial) positive charge in the donor group and a (partial) negative charge in the acceptor group: 
The invention further relates to the use of these catalysts with a donor-acceptor interaction as polymerization catalysts.
Metallocenes as xcfx80 complex compounds and their use as catalysts in the polymerization of olefins have been known for a long time (EP-A-129 368 and the literature cited therein). It is also known from EP-A-129 368 that metallocenes, in combination with alkylaluminum/water as co-catalysts, are effective systems for the polymerization of ethylene, (thus, for example, methylaluminoxane=MAO is formed from approx. 1 mol of trimethylaluminum and 1 mol of water). Other stoichiometric proportions have also already been used successfully (WO 94/20506)). Metallocenes whose cyclopentadienyl skeletons are covalently linked together by a bridge are also already known. EP-A-704 461 may be cited as an example of the numerous patents and patent applications in this field, the linking group mentioned in said patent being a (substituted) methylene group or ethylene group, a silylene group, a substituted silylene group, a substituted germylene group or a substituted phosphine group. EP-A-704 461 also provides the bridged metallocenes as polymerization catalysts for olefins.
Catalysts with a donor-acceptor interaction and their use as polymerization catalysts are known in principle.
Thus, WO-A-98/01455 describes compounds in which a transition metal is complexed with two xcfx80 systems, especially with aromatic xcfx80 systems (metallocenes), and the two systems are reversibly bonded together by at least one bridge containing a donor and an acceptor, the donor or acceptor atoms being bonded as substituents on the xcfx80 systems; it also describes their use as polymerization catalysts.
WO-A-98/45339 describes compounds in which a transition metal is complexed with two xcfx80 systems, especially with aromatic xcfx80 systems (metallocenes), and the two systems are reversibly bonded together by at least one bridge containing a donor and an acceptor, at least one of the donor or acceptor atoms being part of the respective xcfx80 system; it also describes their use as polymerization catalysts.
Patent applications WO-A-98/01483 to WO-A-98/01487 describe industrial polymerization processes which use the described catalysts with a donor-acceptor interaction.
It is known from said documents that the catalysts with a donor-acceptor interaction can advantageously be used as catalysts for the polymerization of olefins.
However, it was a surprise to those skilled in the art that particularly advantageous catalysts with a donor-acceptor interaction could be prepared by selecting special substitution patterns on the acceptor group.
Therefore, the present invention provides transition metal compounds with two xcfx80 systems and at least one donor-acceptor interaction between these xcfx80 systems, characterized in that these transition metal compounds have at least one fluorine-substituted aryl group on at least one acceptor atom.
xcfx80 systems according to the present invention are substituted and unsubstituted ethylene, allyl, pentadienyl, benzyl, butadiene, benzene, the cyclopentadienyl anion and species produced by replacing at least one C atom with a heteroatom, said species preferably being cyclic. The coordination of such ligands (xcfx80 systems) to the metal can be of the "sgr" type or of the xcfx80 type.
Suitable transition metal compounds with at least one donor-acceptor interaction are the transition metal compounds with a donor-acceptor interaction described in patent applications WO-A-98/01455, WO-A-98/45339 and WO-A-98/01483 to WO-A-98/01487, characterized in that these transition metal compounds have fluorine-substituted aryl groups on the acceptor group.
Particularly suitable compounds are the metallocenes of the formula 
in which
CpI and CpII are two identical or different carbanions with a cyclopentadienyl-containing structure, in which one to all of the H atoms can be substituted by identical or different radicals from the group comprising linear or branched C1-C20-alkyl which can be monosubstituted to fully substituted by halogen, monosubstituted to trisubstituted by phenyl and monosubstituted to trisubstituted by vinyl, C6-C12-aryl, halogenoaryl having 6 to 12 C atoms, and organometallic substituents such as silyl, trimethylsilyl and ferrocenyl, and can be monosubstituted or disubstituted by D and A,
D is a donor atom which can additionally carry substituents and which, in its respective bonding state, has at least one free electron pair,
A is an acceptor atom which carries at least one fluorine-substituted aryl group, but preferably exclusively fluorine-substituted aryl groups, as substituents and which, in its respective bonding state, has an electron pair deficiency,
D and A being linked by a reversible coordinate bond in such a way that the donor group assumes a (partial) positive charge and the acceptor group a (partial) negative charge,
M is a metal of groups III-VII of the periodic table of the elements as defined by IUPAC (1985), including the lanthanides and actinides,
X is one anion equivalent and
n is the number zero, one, two, three or four, depending on the charge of M.
The first and second carbanions CpI and CpII with a cyclopentadienyl skeleton can be identical or different. The cyclopentadienyl skeleton can for example be one of the group of cyclopentadiene, substituted cyclopentadiene, indene, substituted indene, fluorene and substituted fluorene, wherein fluorene and substituted fluorene are preferred. There may be 1 to 4 substituents per cyclopentadiene ring or fused benzene ring. These substituents can be C1-C20-alkyl such as methyl, ethyl, propyl, isopropyl, butyl or isobutyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl or eicosyl, C1-C20-alkoxy such as methoxy, ethoxy, propoxy, isopropoxy, butoxy or isobutoxy, hexyloxy, octyloxy, decyloxy, dodecyloxy, hexadecyloxy, octadecyloxy or eicosyloxy, halogens such as fluorine, chlorine or bromine, C6-C12-aryl such as phenyl, C1-C4-alkylphenyl such as tolyl, ethylphenyl, (i-)propylphenyl, (i-/tert-)butylphenyl or xylyl, halogenophenyl such as fluoro-, chloro- or bromophenyl, difluorophenyl, trifluorophenyl, tetrafluorophenyl, pentafluorophenyl, pentachlorophenyl, naphthyl or biphenylyl, triorganylsilyl such as trimethylsilyl (TMS), ferrocenyl, and D or A, as defined above. Fused aromatic rings can also be partially or completely hydrogenated, leaving only the double bond to which both the fused ring and the cyclopentadiene ring contribute. Furthermore, benzene rings, as in indene or fluorene, can carry one or two additional fused benzene rings. Also, the cyclopentadiene or cyclopentadienyl ring and a fused benzene ring can together carry an additional fused benzene ring. In the form of their anions, such cyclopentadiene skeletons are excellent ligands for transition metals, each cyclopentadienyl carbanion of said optionally substituted form compensating one positive charge of the central metal in the complex.
Specific examples of such carbanions are cyclopentadienyl, methylcyclopentadienyl, 1,2-dimethylcyclopentadienyl, 1,3-dimethylcyclopentadienyl, indenyl, phenylindenyl, 1,2-diethylcyclopentadienyl, tetramethylcyclopentadienyl, ethylcyclopentadienyl, n-butylcyclopentadienyl, n-octylcyclopentadienyl, xcex2-phenylpropylcyclopentadienyl, tetrahydroindenyl, propylcyclopentadienyl, t-butylcyclopentadienyl, benzylcyclopentadienyl, diphenylmethylcyclopentadienyl, trimethylgermylcyclopentadienyl, trimethylstannylcyclopentadienyl, trifluoromethylcyclopentadienyl, trimethylsilylcyclopentadienyl, pentamethylcyclopentadienyl, fluorenyl, tetrahydro- or octahydrofluorenyl, fluorenyls and indenyls benzo-fused on the six-membered ring, N,N-dimethylaminocyclopentadienyl, dimethylphosphinocyclopentadienyl, methoxycyclopentadienyl, dimethylboranylcyclopentadienyl and (N,N-dimethylamino-methyl)cyclopentadienyl.
The subscript n assumes a value of zero, one, two, three or four, preferably zero, one or two, depending on the charge of M. Depending inter alia on which of the subgroups they belong to, the above-mentioned metals of groups III-VII can have valencies/charges of two to six, preferably two to four, two of which are compensated in each case by the carbanions of the metallocene compound. Accordingly, in the case of La3+, Zr4+ and Sm2+, the subscript n assumes a value of one, two and zero, respectively.
Reference is made to WO-A-98/45339 for the preparation of the compounds (I).
Other particularly suitable compounds are the metallocenes of formula (II): 
in which
xcfx80I and xcfx80II are mutually different, charged or electrically neutral xcfx80 systems which can be fused with one or two unsaturated or saturated five-membered or six-membered rings,
D is a donor atom which is a substituent of xcfx80I or part of the xcfx80 system of xcfx80I and which, in its respective bonding state, has at least one free electron pair,
A is an acceptor atom which is a substituent of xcfx80II or part of the xcfx80 system of xcfx80II and which, in its respective bonding state, has an electron pair deficiency,
D and A being linked by a reversible coordinate bond in such a way that the donor group assumes a (partial) positive charge and the acceptor group a (partial) negative charge, and at least one of D and A being part of the respective xcfx80 system,
it being possible for D in turn to carry substituents, and A carrying at least one fluorine-substituted aryl group, but preferably exclusively fluorine-substituted aryl groups, as substituents,
it being possible for each xcfx80 system or each fused ring system to contain one or more D or A, or D and A, and
it being possible, in xcfx80I and xcfx80II in the non-fused or fused form, for one to all of the H atoms of the xcfx80 system independently of one another to be substituted by identical or different radicals from the group comprising linear or branched C1-C20-alkyl which can be monosubstituted to fully substituted by halogen, monosubstituted to trisubstituted by phenyl and monosubstituted to trisubstituted by vinyl, C6-C12-aryl and halogenoaryl having 6 to 12 C atoms, and to be monosubstituted or disubstituted by D and A, so that the reversible Dxe2x86x92A coordinate bond is formed between D and A where (i) both D and A are parts of the respective xcfx80 system or fused ring system, or (ii) D or A is part of the xcfx80 system or fused ring system and the other one is a substituent of the non-fused xcfx80 system or fused ring system, or (iii) both D and A are such substituents, whereby, in the case of (iii), at least one additional D or A, or both, is (are) part of the xcfx80 system or fused ring system,
M is a metal of groups III-VII of the periodic table of the elements as defined by IUPAC (1985), including the lanthanides and actinides,
X is one anion equivalent and
n is the number zero, one, two, three or four, depending on the charges of M and those of xcfx80I and xcfx80II.
xcfx80 systems according to the present invention are substituted and unsubstituted ethylene, allyl, pentadienyl, benzyl, butadiene, benzene, the cyclopentadienyl anion and species produced by replacing at least one C atom with a heteroatom, said species preferably being cyclic. The coordination of such ligands (xcfx80 systems) to the metal can be of the "sgr" type or of the xcfx80 type.
More preferred sandwich structures are those in which both the xcfx80 systems are selected from cyclopentadienyl (cp), indenyl (ind) and fluorenyl (flu), especially:
cp-cp
cp-ind
cp-flu
ind-ind
ind-flu
flu-flu
The subscript n assumes a value of zero, one, two, three or four, preferably zero, one or two, depending on the charge of M. Depending inter alia on which of the subgroups they belong to, the above-mentioned subgroup metals can have valencies/charges of two to six, preferably two to four, two of which are compensated in each case by the carbanions of the metallocene compound. Accordingly, in the case of La3+, Zr4+ and Sm2+, the subscript n assumes a value of one, two and zero, respectively.
In the formation of the metallocene structure of formula (I) or (II) above, one positive charge of the transition metal M is compensated by one cyclopentadienyl-containing carbanion. Positive charges still remaining on the central atom M are neutralized by other, usually monovalent anions X, it also being possible for two identical or different such anions to be linked together (dianions ) examples being singly or doubly negatively charged radicals from identical or different, linear or branched, saturated or unsaturated hydrocarbons, amines, phosphines, thioalcohols, alcohols or phenols. Singly charged anions, such as CR3xe2x88x92, NR2xe2x88x92, PR2xe2x88x92, ORxe2x88x92, SRxe2x88x92 etc., can be bonded together by saturated or unsaturated hydrocarbon or silane bridges to form dianions, it being possible for the number of bridging atoms to be 0, 1, 2, 3, 4, 5 or 6, preferably 0 to 4 and more preferably 1 or 2. Apart from H atoms, the bridging atoms can carry further hydrocarbon substituents R. Examples of bridges between the singly charged anions are xe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)3xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, xe2x80x94(CHxe2x95x90CH)2xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94, xe2x80x94Si(CH3)2xe2x80x94 and xe2x80x94C(CH3)2xe2x80x94. Examples of X are hydride, chloride, methyl, ethyl, phenyl, fluoride, bromide, iodide, the n-propyl radical, the i-propyl radical, the n-butyl radical, the amyl radical, the i-amyl radical, the hexyl radical, the i-butyl radical, the heptyl radical, the octyl radical, the nonyl radical, the decyl radical, the cetyl radical, methoxy, ethoxy, propoxy, butoxy, phenoxy, dimethylamino, diethylamino, methylethylamino, di-t-butylamino, diphenylamino, diphenylphosphino, dicyclohexylphosphino, dimethylphosphino, methylidene, ethylidene, propylidene and the ethylene glycol dianion. Examples of dianions are 1,4-diphenyl-1,3-butadienediyl, 3-methyl-1,3-pentadienediyl, 1,4-dibenzyl-1,3-butadienediyl, 2,4-hexadienediyl, 1,3-pentadienediyl, 1,4-ditolyl-1,3-butadienediyl, 1,4-bis(trimethylsilyl)-1,3-butadienediyl and 1,3-butadienediyl. 1,4-Diphenyl-1,3-butadienediyl, 1,3-pentadienediyl, 1,4-dibenzyl-1,3-butadienediyl, 2,4-hexadienediyl, 3-methyl-1,3-pentadienediyl, 1,4-ditolyl-1,3-butadienediyl and 1,4-bis(trimethylsilyl)-1,3-butadienediyl are particularly preferred. Other examples of dianions are those with heteroatoms, for instance of the structure 
the bridge being defined as indicated. Other particularly preferred anions for charge compensation are weakly coordinating or non-coordinating anions of the above-mentioned type or singly negatively charged anions of the CpI, CpII, xcfx80I or xcfx80II type with the possible substitutions already described, which can but do not have to carry additional D or A substituents.
The compounds of general formula (II) can be prepared as described in WO-A-98/45339.
As well as the obligatory first donor-acceptor bond between D and A in formulae (I) and (II), other donor-acceptor bonds can be formed if additional D and/or A are present as substituents of the respective cyclopentadiene systems. All the donor-acceptor bonds are characterized by their reversibility illustrated above. In the case where there are several D or A, these can occupy different positions among those mentioned. Accordingly, the present invention encompasses not only the bridged molecular states but also the non-bridged states. The number of D groups can be identical to or different from the number of A groups. Preferably, the ligands, especially CpI and CpII, are linked together by only one donor-acceptor bridge.
In addition to the D/A bridges according to the present invention, covalent bridges can also be present in formulae (I) and (II). In this case, the D/A bridges strengthen the stereorigidity and thermal stability of the catalyst. By changing between closed and open D/A bonds, it is possible to obtain block polymers of higher and lower stereoregularity. Such blocks can have different chemical compositions in copolymers.
Possible donor groups in formulae (I) and (II) are particularly those in which the donor atom D is an element of group XV, XVI or XVII of the periodic table of the elements and has at least one free electron pair, and in which the donor atom is in a bonding state with substituents in the case of elements of group XV and can be in such a state in the case of elements of group XVI; donor atoms of group XVII do not carry substituents. This is illustrated below using phosphorus, P, oxygen, O, and chlorine, Cl, as examples of donor atoms, where xe2x80x9cSubst.xe2x80x9d represents said substituents, xe2x80x9c-Cpxe2x80x9d represents the bond to the cyclopentadienyl-containing carbanion, a line with an arrowhead denotes a coordinate bond as in formula (I) or (II) and other lines denote available electron pairs: 
Possible acceptor groups in formulae (I) and (II) are especially those in which the acceptor atom A is an element of group XIII of the periodic table of the elements (as defined by IUPAC, 1985), such as boron, aluminum, gallium, indium and thallium, is in a bonding state with substituents and has an electron deficiency.
D and A are linked by a coordinate bond (also known as a dative bond), D assuming a (partial) positive charge and A a (partial) negative charge.
Accordingly, a distinction is drawn between the donor atom D and the donor group and between the acceptor atom A and the acceptor group. The coordinate bond Dxe2x86x92A is formed between the donor atom D and the acceptor atom A. The donor group denotes the unit made up of the donor atom D, any substituents present and the available electron pairs; correspondingly, the acceptor group denotes the unit made up of the acceptor atom A, the substituents and the available electron deficiency.
Donor groups are groups in which the free electron pair is located on N, P, As, Sb, Bi, O, S, Se, Te, F, Cl, Br or I, preference being given to N, P, O and S. Examples of donor groups which may be mentioned are (CH3)2Nxe2x80x94, (C2H5)2Nxe2x80x94, (C3H7)2Nxe2x80x94, (C4H9)2Nxe2x80x94, (C6H5)2Nxe2x80x94, (CH3)2Pxe2x80x94, (CH2H5)2Pxe2x80x94, (C3H7)2Pxe2x80x94, (i-C3H7)2Pxe2x80x94, (C4H9)2Pxe2x80x94, (t-C4H9)2Pxe2x80x94, (cyclohexyl)2Pxe2x80x94,(C6H5)2Pxe2x80x94, (CH3)(C6H5)Pxe2x80x94, (CH3O)2Pxe2x80x94, (C2H5O)2Pxe2x80x94, (C6H5O)2Pxe2x80x94, (CH3-C6H4O)2Pxe2x80x94, ((CH3)2N)2Pxe2x80x94, methyl-containing phosphino groups, CH3Oxe2x80x94, CH3Sxe2x80x94, C6H5Sxe2x80x94, xe2x80x94C(C6H5)xe2x95x90O, xe2x80x94C(CH3)xe2x95x90O, xe2x80x94OSi(CH3)3 and xe2x80x94OSi(CH3)2-t-butyl, N and P each carrying one free electron pair and O and S each carrying two free electron pairs, and the double-bonded oxygen in the last two examples being bonded via a spacer group, as well as systems like the pyrrolidone ring, the ring members other than N also acting as spacers. Acceptor groups are groups in which an electron pair deficiency is present on B, Al, Ga, In or Tl, preferably B, Al or Ga; examples which may be mentioned are (C6F5)2Bxe2x80x94, (C6F5)(alkyl)Bxe2x80x94, (C6F5)HBxe2x80x94, (C6F5)(C6H5)Bxe2x80x94, (CH3)(C6F5)Bxe2x80x94, (vinyl)(C6F5)Bxe2x80x94, (benzyl)(C6F5)Bxe2x80x94, Cl(C6F5)Bxe2x80x94, (CH3O)(C6F5)Bxe2x80x94, Cl(C6F5)Alxe2x80x94, (alkyl)(C6F5)Alxe2x80x94, (C6H5)(C6F5)Alxe2x80x94, (C6F5)2Alxe2x80x94, (C6F5)2Gaxe2x80x94 and (C6F5)(alkyl)Gaxe2x80x94.
Examples of substituents on the donor atoms N, P, As, Sb, Bi, O, S, Se or Te and on the acceptor atoms B, Al, Ga, In or Tl are C1-C12-(cyclo)alkyl such as methyl, ethyl, propyl, i-propyl, cyclopropyl, butyl, i-butyl, tert-butyl, cyclobutyl, pentyl, neopentyl, cyclopentyl, hexyl, cyclohexyl and the isomeric heptyls, octyls, nonyls, decyls, undecyls and dodecyls; the corresponding C1-C12-alkoxy groups; vinyl, butenyl and allyl; C6-C12-aryl such as phenyl, naphthyl or biphenylyl, and benzyl, which can be substituted by halogen, 1 or 2 C1-C4-alkyl groups, C1-C4-alkoxy groups, sulfonate, nitro or halogenoalkyl groups, C1-C6-alkylcarboxy, C1-C6-alkylcarbonyl or cyano (e.g. perfluorophenyl, m,mxe2x80x2-bis(trifluoromethyl)phenyl, tri(C1-C20-alkyl)silyl, tri(C6-C12-aryl)silyl and analogous substituents familiar to those skilled in the art); analogous aryloxy groups; indenyl; halogen such as F, Cl, Br and I; 1-thienyl; disubstituted amino such as (C1-C12-alkyl)2 amino and diphenylamino; tris-(C1-C12-alkyl)silyl; NaSO3-aryl such as NaSO3-phenyl and NaSO3-tolyl; C6H5xe2x80x94Cxe2x89xa1Cxe2x80x94; aliphatic and aromatic C1-C20-Silyl whose alkyl substituents can be octyl, decyl, dodecyl, stearyl or eicosyl in addition to those mentioned above, and whose aryl substituents can be phenyl, tolyl, xylyl, naphthyl or biphenylyl; substituted silyl groups bonded to the donor atom or acceptor atom via xe2x80x94CH2xe2x80x94, for example (CH3)3SiCH2xe2x80x94; and (C1-C12-alkyl)(phenyl)amino, (C1-C12-alkylnaphthyl)amino, (C1-C12-alkylphenyl)2-amino, C6-C12-aryloxy containing the above-mentioned aryl groups, C1-C8-perfluoroalkyl and perfluorophenyl. Preferred substituents are C1-C6-alkyl, C5-C6-cycloalkyl, phenyl, tolyl, C1-C6-alkoxy, C6-C12-aryloxy, vinyl, allyl, benzyl, perfluorophenyl, F, Cl, Br, di(C1-C6-alkyl)amino and diphenylamino, although the acceptor atom carries at least one fluorinated aryl substituent and preferably two fluorinated aryl substituents.
Preferably all the substituents on the acceptor groups are fluorine-substituted aryl groups.
In this context, fluorinated means partially or completely fluorinated, the latter being preferred.
The acceptor group preferably contains an element of group XIII of the periodic table of the elements as defined by IUPAC, 1985.
Aryl is understood as meaning any of the mononuclear or polynuclear aryl radicals known to those skilled in the art, preferably the ones having 6 to 13 C atoms, such as phenyl, naphthyl, fluorenyl and indenyl, which in turn can be further substituted, although they have at least one fluorine substituent and preferably exclusively fluorine substituents. Fluorinated phenyl groups are preferred and perfluorinated phenyl groups are more preferred. In the case of partially fluorinated aryl groups, the remaining substituents, which can be identical or different, independently of one another are preferably selected from the group of hydrogen, C1-C20-alkyl such as methyl, ethyl, propyl, isopropyl, butyl or isobutyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl and eicosyl, C1-C20-alkoxy such as methoxy, ethoxy, propoxy, isopropoxy, butoxy or isobutoxy, hexyloxy, octyloxy, decyloxy, dodecyloxy, hexadecyloxy, octadecyloxy and eicosyloxy, halogen such as chlorine or bromine, C6-C12-aryl such as phenyl, C1-C4-alkylphenyl such as tolyl, ethylphenyl, (i-)propylphenyl, (i-/tert-)butylphenyl and xylyl, halogenophenyl such as fluoro-, chloro- or bromophenyl, naphthyl or biphenylyl, triorganylsilyl such as trimethylsilyl (TMS), ferrocenyl, and D or A, as defined above.
Other possible donor and acceptor groups are those which contain chiral centers or in which 2 substituents form a ring with the D or A atom.
Express reference is made at this point to patent applications WO-A-98/01455, WO-A-98/145339, WO-A-98/101483 to WO-A-98/01487 and EP-A-1 041 086, which, for the purposes of US patent practice, are simultaneously included in the present patent application by way of reference.
The invention further relates to the use of the described transition metal compounds with a donor-acceptor interaction, characterized in that these transition metal compounds have a fluorine-substituted aryl group on at least one acceptor group, in a process for the homopolymerization or copolymerization of one or more olefins, i-olefins, alkynes or diolefins as monomers, or for ring-opening polyaddition, in the gas, solution, bulk, high-pressure or slurry phase, at xe2x88x9260 to +250xc2x0 C., preferably up to +200xc2x0 C., and 0.5 to 5000 bar, preferably 1 to 3000 bar, and in the presence or absence of saturated or aromatic hydrocarbons or saturated or aromatic halogeno-hydrocarbons, and in the presence or absence of hydrogen, these transition metal compounds with a donor-acceptor interaction being used in an amount ranging from 101 to 1012 mol of all the monomers per mol of transition metal compound, and it also being possible for said process to be carried out in the presence of co-catalysts such as Lewis acids, Brxc3x6nsted acids or Pearson acids, or additionally in the presence of Lewis bases.
Examples of such Lewis acids are boranes or alanes such as alkylaluminum compounds, aluminum halides, aluminum alcoholates, organoboron compounds, boron halides, boric acid esters or boron or aluminum compounds containing both halide and alkyl, aryl or alcoholate substituents, as well as mixtures thereof, or the triphenylmethyl cation. Aluminoxanes or mixtures of aluminum-containing Lewis acids with water are preferred. According to current knowledge, all acids work as ionizing agents to form a metallocenium cation which is charge-compensated by a bulky, poorly coordinating anion.
The invention further relates to the reaction products of such ionizing agents with compounds of general formula (I) or (II) according to the invention. They can be described by general formula (III) or (IV): 
in which
Anion represents the whole of the bulky, poorly coordinating anion and Base represents a Lewis base.
The transition metal compounds of general formula (I), (II), (III) or (IV) according to the present invention can exist in either monomeric, dimeric or oligomeric form.
Examples of such poorly coordinating anions are B(C6H5)4xcex8, B(C6F5)4xcex8, B(CH3)(C6F5)3xcex8, 
sulfonates such as tosylate or triflate, tetrafluoroborates, hexafluorophosphates, hexafluoroantimonates, perchlorates, bulky cluster molecular anions of the carborane type, for example C2B9H12xcex8 or CB11H12xcex8, and substituted or unsubstituted cyclopentadienyl, indenyl and fluorenyl anions. Possible substituents are those already described for CpI and CpII. When such anions are present, xcfx80 complex compounds can also work as highly efficient polymerization catalysts in the absence of aluminoxane. This is particularly the case when one X ligand is an alkyl group or benzyl. It can also be advantageous, however, to use such xcfx80 complexes with bulky anions in combination with alkylaluminum compounds such as (CH3)3Al, (C2H5)3Al, (n-/i-propyl)3Al, (n-/t-butyl)3Al, (i-butyl)3Al or the isomeric pentyl-, hexyl- or octylaluminum compounds, alkyllithium compounds such as methyl-Li, benzyl-Li or butyl-Li, or the corresponding organomagnesium compounds, such as Grignard compounds, or organozinc compounds. On the one hand, such metal alkyls transfer alkyl groups to the central metal, and on the other hand they trap water or catalyst poisons from the reaction medium or monomer during polymerization reactions. The following are examples of aluminum or boron compounds from which such anions can be derived:
triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, tri(t-butyl)ammonium tetraphenylborate, N,N-dimethylanilinium tetraphenylborate, N,N-diethylanilinium tetraphenylborate, N,N-dimethyl(2,4,6-trimethylanilinium) tetraphenylborate, trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis-(pentafluorophenyl)borate, tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N-dimethyl(2,4,5-trimethylanilinium) tetrakis(pentafluorophenyl)borate, trimethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, triethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, tripropylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, dimethyl(t-butyl)ammonium tetrakis(2,3,4,6-tetra-fluorophenyl)borate, N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-diethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate and N,N-dimethyl(2,4,6-trimethylanilinium) tetrakis(2,3,4,6-tetrafluorophenyl)borate; dialkylammonium salts such as: di(i-propyl)ammonium tetrakis(pentafluorophenyl)borate and dicyclohexylammonium tetrakis(pentafluorophenyl)borate; trisubstituted phosphonium salts such as: triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(o-tolyl)phosphonium tetrakis(pentafluorophenyl)borate and tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate; tritolylmethyl tetrakis(pentafluoro-phenyl)borate; triphenylmethyl tetraphenylborate (trityl tetraphenylborate); trityl tetrakis(pentafluorophenyl)borate; silver tetrafluoroborate; tris(pentafluorophenyl)borane; tris(trifluoromethyl)borane; and the analogous aluminum compounds.
The transition metal compounds or metallocene compounds according to the present invention can be used in isolated form as pure substances for the (co)polymerization. However, they can also be produced and used xe2x80x9cin situxe2x80x9d in the (co)polymerization reactor in a manner known to those skilled in the art.
Examples of other co-catalysts are aluminoxane compounds, which are understood as meaning compounds of formula (V): 
in which
R is C1-C20-alkyl, C6-C12-aryl or benzyl and
n is a number from 2 to 50, preferably 10 to 35.
It is also possible to use a mixture of different aluminoxanes or a mixture of their precursors (alkylaluminum compounds or alkylaluminum halides) in combination with water (in gaseous, liquid, solid or bound form, for instance as water of crystallization). The water can also be introduced as (residual) moisture in the polymerization medium, the monomer or a support like silica gel or aluminosilicate.
The bonds projecting from the square brackets of formula (V) carry R groups or AlR2 groups as end groups of the oligomeric aluminoxane. Such aluminoxanes are normally present as a mixture of several with different chain lengths. Detailed study has also revealed aluminoxanes of cyclic or cage-like structure. Aluminoxanes are commercially available compounds. In the special case where Rxe2x95x90CH3, they are referred to as methylaluminoxanes (MAO).
The transition metal compound(s) and/or the co-catalyst(s) can be used either as such in homogeneous form or individually or together in heterogeneous form on supports. Such support can be of an inorganic or organic nature, such as silica gel, B2O3, Al2O3, MgCl2, cellulose derivatives, starch and polymers, or else layered silicates like montmorillonites.
The supports are preferably thermally and/or chemically pretreated in order to adjust the water content or the OH group concentration to a defined value or keep it as low as possible. A chemical pretreatment can consist e.g. in reacting the support with alkylaluminum compound. Inorganic supports are usually heated at 100xc2x0 C. to 1000xc2x0 C. for 1 to 100 hours before use. The surface area of such inorganic supports, especially of silica (SiO2), is between 10 and 1000 m2/g, preferably between 100 and 800 m2/g. The particle diameter is between 0.1 and 500 micrometers (xcexc), preferably between 10 and 200xcexc.
Examples of olefins, 1-olefins, cycloolefins, alkynes and diolefins to be reacted by homopolymerization or copolymerization are ethylene, propylene, 1-butene, i-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene, 4-methyl-1-hexene, 1,3-butadiene, isoprene, 1,4-hexadiene, 1,5-hexadiene and 1,6-octadiene, methyloctadienes, chloroprene, acetylene and methylacetylene. xcex1,xcfx89-Diolefins afford the further possibility of a cyclizing polymerization, in which e.g. poly(methylene-1,3-cyclopentane) is formed from 1,5-hexadiene: 
xcex1,xcfx89-Diolefins can also be used to produce long-chain branches.
If trialkylsilyl-substituted xcex1,xcfx89-diolefins are used, a functional group can subsequently be introduced by polymer-analogous reaction. The olefins and diolefins can also be substituted, for example by phenyl, substituted phenyl, halogen, an esterified carboxyl group or an acid anhydride group; examples of compounds of this type are styrene, methylstyrene, chlorostyrene, fluorostyrene, indene, 4-vinylbiphenyl, vinylfluorene, vinylanthracene, methyl methacrylate, ethyl acrylate, vinylsilane, trimethylallylsilane, vinyl chloride, vinylidene chloride, tetra-fluoroethylene, isobutylene, vinylcarbazole, vinylpyrrolidone, acrylonitrile, vinyl ethers, vinyl esters or vinylnorbornene.
Other possible processes according to the present invention are ring-opening polyadditions, for instance of lactones such as xcex5-caprolactone or xcex4-valerolactone, of lactams such as xcex5-caprolactam, of epoxides such as ethylene oxide or propylene oxide, or of other cyclic ethers such as tetrahydrofuran.
Cycloolefins which can be used are described in patent applications WO-98/01483 and WO-98/01484.
Preferred monomers are ethylene, propylene, butene, hexene, octene, 1,5-hexadiene, 1,6-octadiene, cycloolefins, methyl methacrylate, xcex5-caprolactone, xcex4-valerolactone and acetylene. It is possible to carry out said (co)polymerizations in the presence of hydrogen, for instance to adjust the molecular weight.
The homopolymerizations, copolymerizations or polyadditions to be carried out with the optionally supported transition metal compounds with a donor-acceptor interaction according to the present invention are performed under adiabatic or isothermal conditions in the indicated temperature and pressure ranges. This entails high-pressure processes in autoclaves or tubular reactors, solution processes, bulk polymerization processes, slurry phase processes in stirred reactors or loop reactors, and gas phase processes, the pressures for the slurry, solution and gas phases not exceeding 100 bar. Such polymerizations can also be carried out in the presence of hydrogen. All these processes have been known for a long time and are familiar to those skilled in the art.
Through the donor-acceptor bridge, the optionally supported transition metal compounds with a donor-acceptor interaction according to the present invention allow a defined opening of the two cyclopentadienyl skeletons or of the two ligands like a beak, thereby affording not only a high activity but also a high stereoselectivity, a controlled molecular weight distribution and a uniform incorporation of comonomers. A defined beak-like opening also creates room for bulky comonomers. A high uniformity of the molecular weight distribution is also a consequence of the uniform and defined site of the polymerization effected by insertion (single site catalyst).
The D/A structure can effect extra stabilization of the catalysts right up to high temperatures, so the catalysts can also be employed in the high temperature range from 80 to 250xc2x0 C., preferably from 80 to 180xc2x0 C. The possible thermal dissociation of the donor-acceptor bond is reversible and, through this self-organization process and self-repair mechanism, leads to particularly valuable catalyst properties. Thermal dissociation allows e.g. a specific broadening of the molecular weight distribution, facilitating the processability of the polymers. This effect also comes in useful e.g. in the case of catalysts in which the ligands, e.g. CpI and CpII, are linked together by both a covalent bridge and a D/A bridge. The D/A metallocene structures according to the present invention allow e.g. defect-free polyethylene formation to a degree not achieved with conventional catalysts. Accordingly, the ethylene polymers can have extremely high melting temperatures, for example above 135xc2x0 C. to 160xc2x0 C. (maximum of the DSC curve). Compared with the known polyethylenes, such high-melting polyethylenes have e.g. improved mechanical properties and thermostability (sterilizability in medical applications) and thereby, open up possible applications which hitherto seemed impossible for polyethylene and could only be achieved with e.g. high-tacticity polypropylene. Other characteristics are high enthalpies of fusion and high PE molecular weights. In particular, the catalysts according to the present invention afford interference-free growth of the polyethylene chains to give extremely high molecular weights.
Over a wide temperature range, although the PE molecular weight is lowered by raising the polymerization temperature, this occurs without a significant reduction in activity and by and large without going outside the range of high PE molecular weights and high PE melting temperatures which are of industrial value.
It has also been observed that transition metal compounds according to the invention with a donor-acceptor interaction of appropriate symmetry effect a regiospecific (isotactic, syndiotactic) polymerization of suitable monomers, but cause an increasingly unspecific (atactic) linking of the same monomer units in the upper part of said temperature range. This phenomenon has not yet been fully investigated, but it could be consistent with the observation that coordinate bonds which have an ionic bond superimposed on them, such as the donor-acceptor bonds in the metallocene compounds according to the invention, exhibit an increasing reversibility at elevated temperature. Thus, for example, it has been observed in the copolymerization of ethylene and propylene that, with the two comonomers present in equal proportions, a copolymer with a high propylene content is formed at low polymerization temperature, whereas the propylene content drops as the polymerization temperature increases until, ultimately, polymers containing predominantly ethylene are obtained at high temperature.
The reversible dissociation and association of the D/A structure and the mutual rotation of the ligands, for example of the Cp skeletons, which thereby becomes possible can be represented diagrammatically as follows: 
Another valuable property of the supported catalysts with a donor-acceptor interaction according to the present invention is the possibility of self-activation and hence of dispensing with expensive co-catalysts. Here, in the open form of the D/A metallocene compound, the acceptor atom A binds an X ligand to form a zwitterionic structure, thereby producing a positive charge on the transition metal, while the acceptor atom A assumes a negative charge. This kind of self-activation can take place intramolecularly or intermolecularly. This can be illustrated by considering the linking of two X ligands to a chelate ligand, i.e. the butadienediyl derivative: 
The binding site between the transition metal M and H or substituted or unsubstituted C, for instance the C which is still bound in the butadienediyl dianion shown in the exemplary formula, is then the olefin insertion site for polymerization.
The optionally supported transition metal compounds with a donor-acceptor interaction according to the present invention are also suitable for the preparation of both thermoplastic and elastomeric polymers by the various processes mentioned above, providing access both to highly crystalline polymers with an optimized melting range and to amorphous polymers with an optimized glass transition temperature. Also of particular interest are the polymers which can be prepared in this way and have a low glass transition temperature below 0xc2x0 C. and a high melting temperature of  greater than 100xc2x0 C. in one and the same material.
The polymers which can be prepared are outstandingly suitable for the production of all kinds of moldings, especially sheets, tubing, including that for medical purposes, profiles, disks, optical data storage media, cable sheathing, extrudates, surgical implants, ski running surface materials, impact strength modifiers for thermoplasts, for instance for car bumpers, etc.
The Examples which follow illustrate the invention.